Bending machine

ABSTRACT

A method of forming a substantially L-shaped metal bar member having increased thickness in the heel portion thereof which comprises heating a substantially straight body member in the portion forming the heel portion in the L-shaped bar member, bending the bar member in a forming die to at least substantially the required L-shape and while said L-shaped member is retained said die applying pressure to one of the foot or leg portions of the L-shaped bar member to upset softer heated metal into the heel portion in the die cavity.

United States Patent [191 Hornung BENDING MACHINE Stefan Hornung, 25 West St., Brampton, Ontario, Canada [76] Inventor:

[30] Foreign Application Priority Data May 1, 1972 Canada 140946 [52] US. Cl 72/403, 72/389, 72/342, 72/377 [51] Int. Cl 821d 11/10, B21d11/O8 [58] Field of Search 72/389, 384, 377, 342, 72/403, 306, 404; 29/1483 [56] References Cited UNITED STATES PATENTS 3,698,228 10/1972 Campbell 72/377 2,286,893 6/1942 Doissou 72/342 2,023,638 12/1935 Lawson 29/1483 1,754,428 /1930 Huber 29/1483 2,182,958 12/1939 Bullock 72/369 [4 1 Apr. 30, 1974 751,320 2/1904 Mead 72/377 1,891,338 12/1932 Snell 72/342 963,372 7/1910 Johnson et al 72/377 1,862,281 6/1932 Schaefer 72/377 2,193,737 3/1940 Penkala 72/342 Primary ExaminerCharles W. Lanham Assistant Examiner-M. .1. Keenan Attorney, Agent, or FirmSpencer & Kaye [57] ABSTRACT 8 Claims, 5 Drawing Figures TE E lam-.214

' sumsnrs FIGS 1 BENDING MACHINE The present invention relates to the forming of L- shaped metal bar members, particularly L-shaped steel bar members which may be used in fork lift trucks. In particular, the present invention relates to a method and apparatus for forming the L-shaped metal bar members of increased metal thickness in the heel portion thereof with a single heating of the bar and with essentially no consequent grinding of the heel portion of the L-shaped metal bar member.

In the bending of metal bars, such as steel bars, the thickness of the metal in the heel portion of the L- shaped metal bar is of the order of to per cent less than the remainder of the bar which is undesirable and it is desirable to increase the thickness of the metal at such heel portion.

Heretofore, in the formation of L-shaped steel bar members, such as used in fork lift trucks, it has been conventional to provide such increased thickness of metal in the heel portion thereof by first heating a substantially straight steel bar member to soften the metal in that portion of the bar member which in the L.- shaped bar member forms the heel portion, upsetting the steel member in an upsetting machine to produce an enlarged portion in said heel portion and after removal from the upsetting machine, reheating the bar and bending the bar tothe required L-shaped configuration in a forming die. Such a method is subject to some disadvantages including heating of the bar twice due to the use of two types of apparatus, namely an upsetting machine and a forming machine which heating is expensive and involves substantial handling of the metal bar. It is also found that the heel portion of the L-shaped metal'bar'member so produced has to be ground to remove undesirable excess metal therefrom.

The present invention provides a method of forming an L-shap'ed bar member having increased thickness in the heel portion thereof of to percent which method involves a single heating of the substantially straight metal bar member and with which subsequent grinding of the heel portion of the L-shaped metal bar member is substantially.eliminated.

It has now beenfound that when the substantially straight metal bar member, heated in that portion forming the heel portion in the L-shaped bar member, is bent in a forming die to at least substantially the required L-shaped configuration and while retained in said die, pressure is applied to one of the foot or leg portions of the bar member longitudinally thereof, heated metal is upset into the heel portion in the die to form the L-shaped member with a heel portion of increased thickness.

According to the present invention, therefore, there is provided a method of forming a substantially L- shaped metal bar member having a foot portion thereof substantially at right angles to a leg portion thereof which comprises heating that portion of a metal bar member which in the L-shaped bar member forms the heel portion between said foot and leg portions, to soften said metal, bending said bar member in a forming die to substantially said L-shaped configuration and while said L-shaped bar member is retained in said die applying pressure to one end of said foot or leg portions substantially longitudinally thereof to upset heated metal into said heel portion of said L-shaped bar member in said die whereby to increase the thickness of metal in said heel portion.

The present invention also provides an apparatus for forming a substantially L-shaped metal bar member having a foot portion substantially at right angles to a leg portion and having a heel portion of increased thickness comprising a forming die for bending a substantially straight metal bar into a substantially L- shaped configuration, said die comprising a fixed die block and a movable die block, first reciprocal ram means for moving said movable die block between a closed position of said die to cause said bending of said bar and an open position and second reciprocal ram means adapted to, move between an extended and retracted position and arranged in said extended position to apply pressure to one end of said L-shaped bar member in said die longitudinally of one of said foot and leg portions whereby to upset metal into said heel portion of said L-shaped bar member in said die.

The pressure may be applied to the end of said L- shaped member by means of a hydraulic ram as can be the movement of the movable die block of the forming die which is preferably the male die block of the forming die. 7

After the pressure is applied to the foot portion of the L-shaped bar member so that the hot metal is forced into said heel portion of said L-shaped bar member in said die to the desired amount, the pressure is maintained at a constant while the movable die block which previously effected bending of the bar member is retracted. This movable die block then has a cap of precise dimensions placed over it and the movable die block with cap is subsequently moved to the closed position, while the heel portion of the L-s'haped bar member is still hot. This has particular application for the production of forks where a fixed inside radius of the heel portion of the fork is required. Caps producing various required inside radii in the heel portion of the fork are used for this purpose.

' The present invention will be further illustrated by way of the accompanying drawings in which:

FIG. 1 isa side elevation of an apparatus for use in forming an L-shaped steel fork for use in a fork lift truck in accordance with the preferred embodiments of the present invention.

FIG. 2 is a plan view of the apparatus of FIG. 1

FIG. 3 is a section along line 33 in FIG. 2 showing the hydraulic ram used to upset metal into the heel portion of the L-shaped steel fork.

FIG. 4 is a section along the line 4-4 of FIG. 2 showing the front of the hydraulic ram used to bend the steel bar member into the L-shaped fork and,

FIG. 5 is a diagramatic representation of the hydraulic circuitry for actuating the rams in FIGS. 1 to 4.

Referring to FIGSsl to 4 of the drawings, the apparatus comprises a forming die which in FIG. 2 is in the open position. The forming die is composed of a fixed female corner die block 2 and a movable male die block 3. Corner die block 2 is mounted upon'a fixed frame bed 4 and is reinforced by fins 5. The male die block 3 is mounted on the end of piston 6 with a double acting hydraulic ram 7 fixedly mounted on the bed 4 which ram 7 is operated by hydraulic fluid entering and exhausting through ports (not shown). Die block 3 has a groove 10 therein dimensioned to accommodate the width of L-shaped bar member 15 and prevent expansion of the steel traversely with the bar member 15 on 1 closed. Actuation of the ram 12 is effected by entry and exhaustion of hydraulic fluid through ports (not shown).

Referring to FIG. 5 to actuate the hydraulic ram 7 and 12, hydraulic fluid is pumped from a tank 19 by a motor driven pump 20 through check valves 21 via lines 23 either'to solenoid valves 24a and 24b or solenoid valves 25a and 25b. The pumps are connected in parallel to provide for greater volume flow of hydraulic fluid in the system.

When it is required to actuate either the piston 6 of ram 7 or the piston 14 of ram 12 to their extended position, solenoid valves 24a and 24b are respectively actuated whereby fluid passes along lines 26a and 2612 respectively through relief valves 27a and 27b. When the solenoid valves 24a and 24b are not actuated, the hydraulic fluid normally flows back to the tank 19 through lines 28a and 28b respectively. Hydraulic fluid from the rams 7 and 12 on movement of the pistons 6 and 14 to their extended position returns to the tank 19 via lines 29a and 29b respectively.

When it is required to'actuate either the piston 6 of ram 7 or the piston 14 of ram 12 to their retracted posi-. tions, solenoid valves 25a and 25b 'are actuated whereby hydraulic fluid which before actuation returns to the tank through lines 31a and 31b, passes through lines 32a and 32b and relief valves 33a and 33b to the rams. 7 and 12 respectively. Hydraulic fluid is exhausted from the rams through lines 34a and 34b.

In operation of the apparatus, of FIGS. 1 to '4, the steel bar 15, which is shown in dotted outline, is initially straight, is heated in the area thereof, which will form the heel portion 40 of the L-shaped bar to soften the metal. The bar is then laid across the die corner block 2 and the piston 6 of the ram 7 is actuated from the control box 50 to its extended position whereby the male die block 3 bends the bar in the direction shown by the arrows in FIG. 2 to an L-shaped configuration as also shown in'dotted outline. The movement of the bar 15 on being bent to the L-shaped configuration may be facilitated by rollers 41 at either end of the die block 2. Hydraulic ram 12 is then actuated from the control box 50 to move the piston 14 to its extended position to apply pressure longitudinally of the foot portion 16 of the bar 15 to upset softened steel into the heel portion 40 of the L-shapedbar member. While piston 14 of ram 12 is in extended position, piston -6 of heel of L-shaped member. The rams 7 and 12 are subsequently actuated to withdraw piston 6 and piston 14 and re-open the die when cap 43 is removed and the L- shaped member 15 is removed from the die. The apparatus is then in condition for a repeat operation.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of forming a substantially L-shaped metal bar member having a foot portion thereof substantially at right angles to a leg portion thereof which comprises heating a portion of the metal bar member, which in the L-shaped bar member forms the heel portion between said foot and leg portions, to soften'said metal, bending said bar member to at least substantially said L-shaped configuration in a forming die and while said L-shaped bar member is retained in said die applying pressure to one end of said foot or leg portions sub stantially longitudinally thereof to upset heated metal into said heel portion of said L-shaped bar member in said die whereby to increase the thickness of said heel portion.

2. A method as claimed in claim 1 in which the metal is steel. 7

3. A method as claimed in claim 2 in which the L- shaped bar member is of rectangular shaped crosssection and forms a fork for a fork lift truck.

4. A method as claimed in claim 1 in which after upsetting of said metal intosaid heel portion the die is opened, the male forming block of said die is capped by an accurately shaped member and the die reclosed to provide a precise required angle between the leg and foot portions of said L-shaped metal bar member.

5. An apparatus for forming an L-shaped metal bar member having a foot portion and a leg portion, said portions being at right angles to one another and being joined at a heel portion, said heel portion having a thickness greater than the foot or leg portions; said apparatus comprising a forming die having a fixed die block of L-shaped configuration and including a heel forming area; a movable die block of L-shaped configuration; a first reciprocal ram means for moving the movable die block between open and closed positions relative to said fixed die block to cause bending of the metal bar into the L-shape; second reciprocal ram means, movable between retracted and extended positions, for applying axial pressure, in the extended position, to one end of the L.-shaped bar member in the die 7 die block.

ram 7 is then actuated from the control box 50 to its retracted position to open the die. The male die block 3 is then capped by a cap 43 and ram 7 is then actuated 6. An apparatus as claimed in claim 5 in which the movable die block is a male die block of said die.

7. An apparatus as claimed in claim 6 in which said male die block is recessed to hold said bar in said die.

8. An apparatus as claimed'in claim 5 including hydr'aulic means for actuating said first and second rams in predetermined sequence. 

1. A method of forming a substantially L-shaped metal bar member having a foot portion thereof substantially at right angles to a leg portion thereof which comprises heating a portion of the metal bar member, which in the L-shaped bar member forms the heel portion between said foot and leg portions, to soften said metal, bending said bar member to at least substantially said L-shaped configuration in a forming die and while said L-shaped bar member is retained in said die applying pressure to one end of said foot or leg portions substantially longitudinally thereof to upset heated metal into said heel portion of said L-shaped bar member in said die whereby to increase the thickness of said heel portion.
 2. A method as claimed in claim 1 in which the metal is steel.
 3. A method as claimed in claim 2 in which the L-shaped bar member is of rectangular shaped cross-section and forms a fork for a fork lift truck.
 4. A method as claimed in claim 1 in which after upsetting of said metal into said heel portion the die is opened, the male forming block of said die is capped by an accurately shaped member and the die reclosed to provide a precise required angle between the leg and foot portions of said L-shaped metal bar member.
 5. An apparatus for forming an L-shaped metal bar member having a foot portion and a leg portion, said portions being at right angles to one another and being joined at a heel portion, said heel portion having a thickness greater than the foot or leg portions; said apparatus comprising a forming die having a fixed die block of L-shaped configuration and including a heel forming area; a movable die block of L-shaped configuration; a first reciprocal ram means for moving the movable die block between open and closed positions relative to said fixed die block to cause bending of the metal bar into the L-shape; second reciprocal ram means, movable between retracted and extended positions, for applying axial pressure, in the extended position, to one end of the L-shaped bar member in the die longitudinally of one of said foot and leg portions so as to upset metal into the heel forming area of the fixed die block.
 6. An apparatus as claimed in claim 5 in which the movable die block is a male die block of said die.
 7. An apparatus as claimed in claim 6 in which said male die block is recessed to hold said bar in said die.
 8. An apparatus as claimed in claim 5 including hydraulic means for actuating said first and second rams in predetermined sequence. 